Dell 19.5V-4.62A 90 Watt AC Adapter Slim Series

Thanks for the info.

Is there a way to tell if I currently have a 65-watt or a 90-watt?

The 65W put out a lower power level than the 90. There is no harm in using a 90W adapter in place of a 65, but you SHOULD NOT use a 65W adapter in place of a 90W unit. The system may not run at full speed, the adapter may overheat, and the battery will charge more slowly (or may not charge at all when the system is powered on) if you do.